Quectel RG520N-AT - Page 47

5G Module Series
RG520N-AT_Hardware_Design 46 / 109
Test points must be reserved for debugging and firmware upgrading in your designs. The following figure
shows the reference circuit of USB interface.
USB_DP
USB_DM
GND
USB_DP
USB_DM
GND
R1
R2
Close to Module
R3
R4
Test Points
TVS Array
NM_0R
NM_0R
0R
0R
Minimize these stubs
Module
Host
USB_VBUS
VDD
USB_SS_TX_P
USB_SS_TX_M
USB_SS_RX_P
USB_SS_RX_M
C1
C3
C4
220 nF
220 nF
220 nF
220 nF
USB_SS_RX_P
USB_SS_RX_M
USB_SS_TX_P
USB_SS_TX_M
C2
Figure 18: Reference Circuit of USB Application
To ensure the signal integrity of USB data traces, you must place R1, R2, R3, R4, C1 and C2 close to the
module, C3 and C4 close to the host, and keep these resistors close to each other. Keep the extra stubs
of trace as short as possible.
The following principles should be complied with when designing the USB interface, to meet USB
specifications.
⚫ It is important to route the USB signal traces as differential pairs with ground surrounded. The
impedance of USB 2.0 differential trace is 90 Ω. The impedance of USB 3.1 differential trace is 85 Ω.
USB_SS_TX_P
91
AO
USB 3.1 SuperSpeed
transmit (+)
Requires differential
impedance of 85 Ω.
USB 3.1 Gen 2 compliant.
USB_SS_TX_M
89
AO
USB 3.1 SuperSpeed
transmit (-)
USB_SS_RX_P
88
AI
USB 3.1 SuperSpeed
receive (+)
USB_SS_RX_M
86
AI
USB 3.1 SuperSpeed
receive (-)